key: cord-273090-fdzkfo1u
authors: He, Susu; Zhou, Chao; Lu, Dongqing; Yang, Haihua; XU, Hailing; Wu, Guixian; Pan, Weijia; Zhu, Rui; Jia, HaiJian; Tang, Xinni; Chen, Xi; Wu, Xiaomai
title: Relationship between Chest CT manifestations and immune response in COVID-19 patients
date: 2020-06-20
journal: Int J Infect Dis
DOI: 10.1016/j.ijid.2020.06.059
sha: 
doc_id: 273090
cord_uid: fdzkfo1u

Abstract Objectives To study the and correlations of lymphocytes and cytokines between changes of lung lesion volumes in patients with COVID-19, and to predict their correlation. Methods 93 patients with COVID-19 were divided into mild and severe groups. The data of lymphocyte subgroups and cytokines were collected, the imaging characteristics were measured and correlation analysis was performed to analyze the differences. Results 60 mild and 33 severe patients were included, Lymphocyte subsets decreased in both groups. The percentages of reduction of absolute lymphocytes value in mild and severe groups were 32% and 64% respectively. The lung CT lesion volume of all patients was 241.45 ± 282.92 cm3, among which the mild group was 151.29 ± 226.04 cm3 and the severe group was 405.38 ± 304.90 cm3, respectively. In critically ill patients, the decrease of absolute value of CD4 + T cells and increase of IL-6 level are significantly correlated with the volume of lung lesions. Conclusions The absolute values of CD3+, CD4+, and CD8 + T cells are lower in patients with COVID-19, the levels of IL-6 and IL-10 are increased. The severity of lung lesions predicts poor clinical outcomes and may be a predictor of the transition from mild to severe.

A group of unexplained pneumonia patients has been found in Wuhan, China since December 2019. Some of them have developed severe symptoms of acute respiratory infections, and some rapidly developed into acute respiratory distress syndrome and other serious complications. The Chinese Center for Disease Control and Prevention (CDC) identified a novel β-corovirus in airway epithelial cells of patients and was named 2019-nCoV by the WHO [1] . So far, infections have also been found in other cities in China and more than a dozen countries in the world, and there is increasing evidence that human-to-human transmission exists [2] [3] [4] .

Early studies have shown that increased pro-inflammatory cytokines in the serum of patients with SARS are associated with lung inflammation and extensive lung injury [8] . There have been many reports that most of the 2019-nCoV patients have chest CT manifestations of pneumonia, typically showing bilateral ground-glass shadows and patchy shadows, and a few can also appear as consolidation shadows and interstitial lesions, the laboratory showed that the lymphocytes count in most patients decreased [6] [7] [8] [9] , with gradually worsened the disease, the lymphocytes absolute count continued to decline [9] , and has been There are reports in the literature that the proinflammatory cytokines IL-2, IL-6, IL-8, IL-10, and TNF-α are elevated in some 2019-nCoV patients [7] [8] . The purpose of this study is to investigate changes in lymphocytes counts and cytokines levels induced by 2019-nCoV and their effects on lung lesions, to determine the severity of the disease, and to select markers that could prompt early clinical intervention.

This study was a single-center retrospective study and recruited 93 2019-nCoV patients who were admitted to Taizhou Public Health Medical Center in Zhejiang Province from January 17 to February 12, 2020. Taizhou Public Health Center is the designated hospital for 2019-nCoV patients in Taizhou City, Zhejiang Province. According to the arrangements of the Chinese government, when all patients diagnosed with 2019-nCoV J o u r n a l P r e -p r o o f pneumonia in Taizhou City according to the WHO Interim Guidelines [3] , all of them were obligated to be transferred to this center, followed by standard diagnosis and treatment. RT-Realtime PCR confirmed that all patients were positive for the novel coronavirus nucleic acid. All patient data have been reported to the WHO. Patients were divided into mild and severe (including severe and critical) groups according to the WHO NCP Interim Guidelines. This study was approved by the Ethics Committee of Enze Hospital, Zhejiang Enze Medical Group (Center), and written informed consent was obtained from the patients before retrospective data collection.

The patient's clinical symptoms, signs, laboratory test results, and treatment measures are all from electronic medical records. Data related to other medical institutions are obtained directly by communicating with their attending physicians. The clinical results were followed up until February 27, 2020. The laboratory tests involved in this study include the absolute value of lymphocytes, CD3+T, CD4+T, CD8+T, B cell, NK cell, IL-2, IL-4, IL-6, IL-10, TNF-α , IFN-γ.

We defined the patients' lung lesions including ground glass shadows, patch shadows, consolidation areas, interstitial lesions, and nodular shadows as our regions of interest (ROI) (Figure 1 ). In order to ensure the accuracy of the measurement, we have three physicians (all with more than 5 years of experience) to determine and measure the RIO area. The number of measurements for each patient depends on the extent and scope of the lung lesions. The average value is the final measurement value.

Baseline characteristics, laboratory findings and radiology were compared using Chisquare analysis. The variables of CT lesion area, lymphocytes and cytokines were compared using independent group t tests. The relationship of CT lesion area and peripheral blood lymphocytes were examined using the χ2 test. All statistical analyses were performed using SAS version 7.0 software. For unadjusted comparisons, a 2-sided α of less than .05 was considered statistically significant. 

93 patients with 2019-nCoV infection were include in our study. Patients were divided into mild and severe groups according to the WHO NCP Interim Guidelines. Table 1 summarizes the characteristics of 2019-nCoV patients, among which 60 were in the mild group (65%). 33 people were in the severe group (35%). The median age of the patients in the mild group was 44(44.5±12.5)years-old, and the median age of the patients in the severe group was 54(53.9±12.5)years. There was no statistical difference.

This study shows that the most common symptoms of patients with this disease are fever (75%), followed by cough (65%), fatigue (24%), dyspnea (22%), myalgia (6%), sore throat (12%), and diarrhea (9%) are rare. Twenty-four patients had at least one underlying disease, including 14 cases of hypertension, 7 case of diabetes and 2 cases of COPD. The severe group (42%) was statistically different from the mild group (17%).

Among them, the number of patients with diabetes in the severe group was more than that in the mild group, P <0.05 Table 2 shows the results of laboratory tests after admission. 40/ 93 patients (43%) had an absolute decrease in lymphocytes, among which 19(32%) patients were mild and 21(64%) patients were severe, there were statistical differences. T-cell subsets were tested in 73 patients, including 48 mild patients and 25 severe patients. Among them, the absolute value of CD8 + T cell decreased in 34 (47%) patients, among which 17 patients were mild (35% of total mild patients), 17 cases of severe cases (68% of severe cases), P <0.05, there is a statistical difference. It was observed that some patients have decrease in CD3+ T cell (55%), CD4+ T cell (53%), B cell (21%), and NK cell (32%), but there was no statistical difference between mild or severe groups. All 93 patients were tested for IL-2, IL-4, IL-6, IL-10, TNF-α, and IFN-γ. There were 72 (77%) patients with elevated IL-6, of which 42 were in mild patients (70% of the mild group) and 30 were in severe patients (91% of the severe group). There was a statistical difference between the two groups. There were 29 (31%) patients with elevated IL-10, J o u r n a l P r e -p r o o f of which 13 were mild (22% of the mild group) and 16 were severe (48% of the severe group). There was a statistical difference between the two groups. IL-2, IL-4, TNF-α, and IFN-γ were normal in all patients.

All patients underwent chest CT scans, and 71 (76%) patients had lesions involving 3 or more lung lobes, including all 33 critically ill patients. Lung CT showed groundglass opacity or patchy shadowing in 88 (95%) patients, 50 (54%) patients with thickened lobular septum, 40 (43%) with consolidation, and 25 (27%) combined with nodular shadows, there were 4 (4%) mild patients with no abnormal chest CT. Among them, severe patients had much more chances of consolidation than mild patients, which was statistically different ( Table 3) . Table 4 , the absolute values of lymphocytes, CD3+T cell, CD4+T cell, and CD8+T cell in the severe group had more significant decrease than those in the mild group, (P <0.05). The levels of IL-6 and IL-10 in the severe group were higher than those in the mild group, which was statistically significant (P <0.05). The lesion volume in lung CT in all patients were 241.45 ± 282.92 cm 3 . The volume of lung lesions in the light group was 151.29 ± 226.04 cm 3 , which was significantly smaller than that in the severe group (405.38 ± 304.90 cm 3 , P <0.001).

In the mild group, the volume of the lung lesions was related to the absolute value of CD3+T cells and CD8+T cells, in severe patients, however, the volume of the lung lesions was correlated to the absolute value of CD4+T cells, P <0.05. Although all patients' NK cells were within the normal range, the absolute value of the NK cells in the severe group was negatively correlated with the volume of lung lesions (p <0.05).

(table 5) . No matter in the light group or the severe group, the size of the lung lesion volume was positively correlated with the increase of IL-6, P <0.05 (Table 6 ).

Similar to the study by Wang et al. [9] , severe patients are generally older and have more comorbidities, which suggests that age and comorbidities are risk factors for adverse outcomes.

The clinical characteristics of 2019-nCoV infection are similar to those of previous beta coronaviruses such as SARS-CoV and MERS-CoV infection. In this study, the majority of patients presented with fever and dry cough, and a few were dyspnea, sore throat, nasal congestion, and diarrhea. The lung CT of most patients showed bilateral distribution of ground glass shadow and patchy shadow and lobular septum thickening, and Patients can show consolidation shadows and nodular shadows, and a few patients have no obvious abnormalities in lung CT, which is similar to previous studies [6] [7] [8] [9] .

The average age in this study is 49 years old. There is no significant difference between men and women, suggesting that 2019-nCoV is generally susceptible to the population, which is different from previous reports [6] . Similar to the study by Wang et al. [9] , severe patients are generally older and have more comorbidities, which suggests that age and comorbidities are risk factors for adverse outcomes.

Lymphocyte subsets play an important role in human cellular immune regulation.

Studies have shown that the drastic reduction in the total number of lymphocytes indicates that coronavirus has consumed many immune cells and inhibited the body's cellular immune function. The damage of T lymphocytes may be an important factor leading to the deterioration of patients' conditions [13] . Recently, the literature also pointed out that the decline of the absolute value of lymphocytes and the severity of chest CT manifestations predict poor clinical outcome [6] , which is consistent with the current literatures [14] . Our study also showed that the absolute number of lymphocytes decreased in most patients, including CD3, CD4, CD8, B cells, and NK cells. In comparison with mild and severe patients, we found that CD4 + T, CD8 + T decreased, IL -6, IL-10 elevation is statistically significant, and it is found that patients with more profound lung lesions have more severely reduced lymphocytes counts, and the reduction is negatively correlated to the area of lung lesions. It can be seen that, like This study found that the serum levels of IL-2, TNF-α, and IFN-γ were normal in patients, which is different from MERS-CoV infection and recent studies [12, 7, 16] , suggesting that 2019-nCoV infection may not cause an inflammatory response. Thelper-1 (Th1) cells. Similar to previous studies [7] , 2019-nCoV infection led to an increase in IL-6 and IL10 associated with T-helper-2 (Th2), which inhibits inflammation, and the levels of IL-6 and IL-10 increased significantly in severe patients compared with mild patients, which is different from SARS-CoV infection [10] . The results of this study indicate that Th2-cell-associated IL-6 and IL-10 are involved in humoral immunity in patients with severe disease, which is higher than those in patients with mild disease, indicating that patients with severe 2019-nCoV infection have stronger immune suppression. The above results suggest that we need to further study the response characteristics of Th1 and Th2 in 2019-nCoV infection to clarify its pathogenesis Our research shows that Th2 related cytokines IL-6, IL-6 and IL-10 are low or normal, which is similar to previous SARS and other viral pneumonia findings [14] (6, 10 are not similar), but there are also studies showing that 2019-nCoV Infection causes increased secretion of T-helper-2 (Th2) cytokines (such as IL-4 and IL-10) that suppress inflammation [7] , which is different from SARS-CoV infection [10] . The results of this study indicate that Th2 cell-associated IL-6 and IL-10 in the severe group are higher than those in the mild group, indicating that the immunosuppressive effect of patients J o u r n a l P r e -p r o o f with severe infection is stronger. The above results suggest that we need to further study the response characteristics of Th1 and Th2 in 2019-nCoV infection to clarify its pathogenesis.

Infection with SARS-CoV [8] , MERS-CoV [10] , and 2019-nCoV can induce an increase in cytokines, and early studies have shown that increased inflammatory cytokines are related lung inflammation and acute lung damage [8] , IL-6 may play a pro-inflammatory role in pulmonary inflammation [11] , and is closely related to mortality in ARDS patients [15] . Our study observed that IL-6 increased significantly in patients with severe inflammation in the lungs, and it's level changes accordingly as of inflammation increases and absorbs. It is suggested that the IL-6 monoclonal antibody may reduce lung inflammation or may be used to treat 2019-nCoV infection. It also suggests that for severe patients, early detection, early application of immunoglobulins to boost patients' anti-infective ability, early application of corticosteroids, reduction of alveolar damage and pulmonary exudation may improve patient prognosis.

Our study is not flawless. First, as a retrospective study, some clinical data is not complete. Not all patients were tested for lymphocyte subsets and cytokines. A lot of cytokines are not included, for example IL-1β, IL-8, IL-12, IP-10, CSF, and transforming growth factor (TGF),.it is therefore difficult to clearly explain the changes of various cytokines caused by 2019-nCoV infection and their impact on lung inflammation. In the future, more cytokine and chemokine studies are needed in prospective studies to clarify their potential as a prognostic indicator of the severity of 2019-nCoV disease. We will continue to follow-up of cured and discharged patients, and regularly monitor the peripheral blood lymphocyte subsets, cytokines, chest CT, and lung function to reveal the impact of 2019-nCoV infection on human long-term survival.

We declare that we have no financial and personal relationships with other people 

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This study was funded by the Science and Technology Foundation of Taizhou (number 1801KY18). We thank all patients involved in the study, and we acknowledge all health-care workers involved in the diagnosis and treatment of patients in Taizhou, China.
